Releasing collar



March 24, 1970- E. BURNS RELEASING COLLAR 2 She'ets-Sheet 1 Filed April24. 1968 1 if March 24, 1970 E. BURNS 3,502,353

RELEASING COLLAR Filed April 24. 1968 2 Sheets-Sheet 2 United StatesPatent O 3,502,353 RELEASING COLLAR Erwin Burns, Los Angeles, Calif.,assgnor of one-half to Audrey S. Carr, Anaheim, Calif. Filed Apr. 24,1968, Ser. No. 723,779 Int. Cl. F161 35/00 U.S. Cl. 285-2 15 ClaimsABSTRACT OF THE DISCLOSURE An elongate substantially vertical fluidconducting rotary tubing string for use in oil Wells comprising, aplurality of axially aligned, interconnected steel tubing sections ofsubstantially uniform weight and tensile strength, said string being ofpredetermined length and weight and subjected to varying predetermineddeadweight tensile forces which increase uniformly downwardly throughoutthe longitudinal extent of the string, an elongate, fluid conductingreleasing collar with separable upper and lower sections and setreleasing means therebetween engaged in the string a predetermineddistance below the upper end thereof with its upper and lower sectionsconnected with the opposing lower and upper ends of a predetermined pairof adjacent tubing sections, said set releasing means being set torelease the sections of the collar before the cumulative forces ofvertical pulling forces applied to the upper end of the string, thedeadweight of the portion of the string below the collar and apredetermined maximum of supplemental frictional and holding forcesacting on and through the portion of the string below the collar exceedsthe tensile limits of the portion of the string above the collar, saidupper and lower sections being telescopically engaged for free relativeaxial shifting, said holding means including one or more shear pinsengaged in and extending between the upper and lower sections, saidcollar further including drive means to prevent relative rotationbetween the sections and sealing means to prevent the leakage of fluidwithin the collar outwardly between the sections.

This invention has to do with a novel well tool and is more particularlyconcerned with a tubing safety joint or releasing collar, the purpose ofwhich is to effect breaking or separation of a string of run-in tubing,in a well structure, at a predetermined point and by the application ofpredetermined tensile forces in and through the tubing string.

In modern oil well drilling practices, it is common to direct the courseof a Well laterally and downwardly relative to the surface site of thewell. Such directional drilling results in a well bore which is normalor vertical at its upper end and which turns laterally in a singleparabolic curve so that the lower end is downwardly and laterallyinclined, or results in a well bore normal at its upper end and whichturns laterally outwardly and then downwardly again in a compound curvewith its lower end substantially vertical, but radially offset from itsupper end.

As a result of the above-noted irregular and oftentimes tortuous coursesin which oil wells are established, the strings of tubing and the likewhich must be run into the wells in the course of completion, productionand service, do not hang or depend freely in and through the wells, butlay and bear against the sides of the well bores and ICC are bound orurged into pressure bearing engagement with the bores of the wells whencompressive or tensional forces are applied thereto for the purpose ofrunning such strings into or pulling them from their related wells.

The above-noted bearing and binding contact of tubing strings indirectionally drilled wells frequently creates drag and frictionalresistance on and through the tubing strings which is excessive andwhich is such that slight, ordinarily acceptable and anticipatedbinding, packing or freezing of well tools or apparatus on the lowerends of such strings, in the bottoms of the wells, create cumulativefrictional and holding forces which exceed the tensile strength of thetubing strings. When such conditions are established and attempts aremade to pull such strings from their related wells, the tubing stringsbreak or part. Such breaking or parting of such strings under theabove-noted conditions, seldom occurs at or in close proximity to thetools at the lower ends thereof, but normally occurs a substantialdistance above the tools and oftentimes several thousands of feet abovesuch tools. After breaking or parting of a tubing string, as noted, itis necessary for the drilling crew to carry out the extremely costly andtime-consuming cleaning retrieving operation which consists of cuttingand fishing out the leftin tubing and related tool, a piece at a time,and hailing, backscuttling, or otherwise cleaning the bore, as suchcutting and fishing operations continue.

In the East Wilmington Oil Field, in the State of California, abouttwenty-two oil wells are being established or serviced each month. Eachmonth in about live or six of these wells, the tubing string separatesas a result of the above-noted conditions and the noted cleaning andretrieving or fishing operations must be performed thereon. The costs ofcorrecting each such failure varies, as a general rule, between$5,000.00 and $30,000.00, with an estimated total cost of approximately$100,000.00 each month in this single oil field.

An object of my invention is to provide a novel releasing collar adaptedto be engaged between predetermined sections or stands of tubing makingup a run-in string of tubing, which is such that it will break, separateor part when predetermined tensile forces are exerted through the tubingstring and said collar whereby the point of separation of the tubingstring in the well can Ibe predetermined and controlled so as to makecleaning and retrieving of tubing and equipment left in the well,easier, quicker and less costly than present practices afford.

Another object of my invention is to provide a releasing collar of thecharacter referred to which is such that it can safely and effectivelyhandle all hydraulic pressures to be encountered without failure orleaking and a structure which is such that it will hold and withstandall normal and anticipated torsional forces to be encountered withouttwisting, turning or otherwise failing.

Still another object of the present invention is to provide a releasingcollar of the character referred to which is such that the axial forcesrequired to cause separation of its relatively separable parts and/orportions can be .easily and quickly varied, as circumstances requiredand without requiring extensive, costly and time-consuming overhaulingand/or modification of the construction.

It is an object of my invention to provide a novel well servicingappartus, including an elongate run-in string made up of a plurality ofstands of tubing and engageable in a well to extend from the upper endthereof to the lower end thereof, a well servicing tool at the lower endof the run-in string and one or more releasing collars as provided bythis invention between predetermined stands of tubing and adapted toseparate and effect parting of the run-in string at predetermined pointsalong its longitudinal extent when the run-in string is subjected topredetermined maximum tensile forces.

An object of the invention is to provide a novel run-in string of tubingfor well servicing tools including a plurality of axially aligned,interconnected stands of tubing and one or more collars as provided bythis invention engaged between predetermined adjacent tubing stands.

The foregoing and additional objects and features of my invention willbe fully understood from the following detailed description of typicalpreferred forms and applications of my invention, throughout whichdescription reference is made to vthe accompaying drawings, in which:

FIG. 1 is a view of a well structure with a run-in string of tubingengaged therein and having a well servicing tool carried thereby andhaving my new releasing collars engaged therein;

FIG. 2 is an enlarged detailed sectional view taken as indicated by line2-2 on FIG. l;

FIG. 3 is a view similar to a portion of FIG. 2 and showing parts inanother position;

FIG. 4 is a sectional view taken as indicated by line 4-4 on FIG. 2;

FIG. 5 is a sectional view taken as indicated by line 5 5 on FIG. 3;

FIG. 6 is a sectional view taken as indicated by line 66 on FIG. 2;

FIG. 7 is an enlarged view of a portion of the structure shown in FIG.6;

FIG. 8 is an elevational view of another form of the invention, withportions broken away to illustrate details of the construction;

FIG. 9 is an isometric view of parts provided in the constructionillustrated in FIG. 8; and,

FIG. 10 is an isometric view showing a subassembly of the constructionshown in FIG. 8.

In FIG. 1 of the drawings, I illustrate typical well structure W andshow a run-in tubing string S engaged therein and carrying a suitablewell servicing tool T at its lower end. The string of tubing S is shownprovided with two releasing collars R as provided by my invention.

The well structure W illustrated in the drawings is a typicaldirectionally drilled well structure and includes a bore 10 having astraight, vertical upper end portion 11 entering the surface 12 of theearths formation, a straight, vertical lower end portion 13 extendinginto an oil producing formation 14 below the earths surface 12 and on avertical axis laterally offset from the upper portion 11 and adownwardly and laterally and, thence, laterally and downwardly compoundcurved central portion 15 between the upper and lower portions 11 and13. The well bore is provided with and supported by a casing 16, whichcasing extends from the top of the bore into the lower portion 13thereof and is shown terminating adjacent the top of the productionformation 14. In the case illustrated, the lower end portion of thebore, below the casing and within the formation 14, is provided with aperforated liner 17 suspended from the lower end of the casing by aliner hanger and packer assembly or tool 18.

The run-in string S is made of a plurality of elongate lengths or standsof uid conducting tubing arranged and connected in end-to-endrelationship. The tubing string is considerably less in diametric extentthan the inside diameter of the easing and the string is greater inlongitudinal extent than the casing. The run-in string S enters the topof the well Casing and extends downwardly and longitudinallytherethrough and is provided at its lower end with a servicing tool T.In the case illustrated, the tool T is a gravel packing tool and isemployed to distribute and deposit gravel pumped and circulateddownwardly through the string S, into the perforated liner 17 and,thence, into the portion of the well bore in the formation 14 about theliner. The gravel pack is indicated by stippling in FIG. 1 of thedrawings.

When gravel packing a well structure with the means illustrated in thedrawings and described above, it is not infrequent that the gravel, asillustrated, migrates back up' and into the casing and becomes socompacted and lodged in the liner and the casing, about the tool and thelower end of the string S, as to freeze and hold the tool and the lowerend of the string S in the well structure with such force as willprevent the withdrawal of the string and tool without breaking andparting the run-in string, some place along its longitudinal extent.

More particularly, the holding force of the compacted gravel on andabout the tool and string, while not excessive in itself, is cumulativewith the deadweight force of the string itself and with the frictionalor dragging forces occurring between the string S and the casing, andthe cumulative forces are greater and exceed the tensile limits of thetubing making up the string. As a result of the above, it will beapparent that when in a situation such as illustrated and describeddevelops, the tubing string usually parts in the upper portion of thewell structure where the cumulative forces are the greatest.

With present practices, when the string S parts or breaks in the mannerset forth above, it is necessary that the portion of the string S andthe tool T, left in the well, be removed. Such removal is carried out bydisassembly of the string S, a stand at a time, where possible, orcutting the string up, and fishing out or retrieving the stands or cutupsections of tubing from the well. When such retrieving operation reachesthat zone in the well Where the gravel is packed and is holding thestring and tool, the retrieving operation requires Ibailing orcirculating the undesired and trouble-causing gravel out of the well andbecomes more complicated and costly.

It is well-known to those skilled in the art and will be readilyapparent to those with limited knowledge in the art, that a retrievingor fishing operation such as referred to above is extremely costly andtroublesome.

It is to be understood that the particular gravel packing operationreferred to above, is only illustrative of one well servicing operationin which tools and related tubing strings can and do become stuck orfrozen in wells and which results in breaking and separating of tubingstrings and requires shing or retrieving operations similar to thatoperation referred to above.

A major diiculty or problem encountered in the well drilling andservicing art, where the above-noted type of adverse situation develops,is: it cannot be readily determined or controlled at which point arun-in string will break or part. Under present practices, when a toolbecomes stuck in a well, the driller simply pulls on the run-in stringuntil it parts and in doing so hopes that it will part in its lowermostportion. As noted above, due to the cumulative nature of the forcescoming into play, such hopes or wishes of a driller are seldom granted.

In light of the above, it has lbeen determined that by provision of asuitable and proper releasing means, in the lower end portion of arun-in string, parting of the string at the lower end portion thereof,when that portion of the string and a related tool become stuck orfrozen in a well, can be assured and that undesired breaking and partingof the string a substantial distance above the bottom of the well can beprevented.

By providing such a releasing means, the necessity of fishing orretrieving is not eliminated, but is effectively controlled and thepossible extent of such operaionls is maintained at predeterminedminimal and tolerable eve s.

The releasing collar R that I provide and which is illustratedthroughout the drawings is adapted to be engaged in a run-in string S,between adjacent tubing stands to become a part thereof. The collar R issuch that it allows for free uninterrupted flow of uid through thestring, allows for normal turning of the string and withstands thosetorsional forces to be encountered. Further, it is such that it willwithstand limited predetermined tensile forces in and through the stringand will yield and allow for separation or parting of the string whensaid tensile forces are exceeded.

The collar R is shown as including an upper male section U and a lowerfemale section L. The upper male section U is an elongate verticallyextending cylindrical part having a central longitudinal flow passageequal in diametric extent with the flow passage in the tubing standsmaking up the string S; an upper Ibox portion 21, a central internallythreaded upwardly opening box 22 in said `box portion threadedlyreceiving a pin 23 on the lower end of that stand of tubing 24 relatedto the upper end of the collar, upper and lower central portions 25 and26 and a lower portion 27. The upper central portion 24 is less indiametric extent than the upper box portion 21 and cooperates therewithto dene an annular stop shoulder 28, which shoulder is shown as beingdownwardly and inwardly inclined.

The portion 24 is of substantial longitudinal extent and is providedwith threads 29 about its lower end portion. The threads 29 projectradially outward from their related portion of the section U, that is,the minor diameter of the threads 29 is equal or greater than theoutside diameter of the portion 25 of the section U.

The lower central portion 26 of the section U is less in diametricextent than the upper central portion 25 and joins the lower externallythreaded end portion of the portion 25 to define a downwardly disposedannular stop shoulder 30. The portion 26 is of considerable longitudinalextent and is provided, in its upper portion with at least one andpreferably two or more axially spaced radially outwardly opening shearpin receiving grooves 31.

The lower portion of the lower central portion 26 of the section U isprovided with a plurality (three) of circumferentially spaced, elongate,longitudinally extending, radially outwardly disposed flats 32, whichflats form a part of a modified spline construction for establishingtorsional drive means between the sections U and L.

In practice, the flats 32 can extend laterally uninterrupted to convergewith the outer cylindrical surface of the portion 26 of the section U orcan, as illustrated in FIG. 7 of the drawings, be in the nature of veryshallow and very wide longitudinally extending flat bottomed grooves inthe exterior of the section U, and such that they dene, in addition tothe outwardly disposed ats 32, laterally spaced, laterally inwardlydisposed opposing shoulders 33, at each side of the flats. The lower endportion 27 of the section U is less in diametric extent than the lowercentral portion 26 and continues or extends downwardly therefrom. Theportion 27 is of reduced diameter to facilitate establishment of theflats 32 and is such that the plane of the ats are substantiallytangential with the exterior of said portion 27. The portion 27terminates at a at downwardly disposed bottom end 34 and is providedwith a plurality of axially spaced, radially outwardly opening sealingring receiving grooves 35 throughout its longitudinal extent.

From the foregoing, it will be apparent that the upper section of mycollar R is an extremely simple, easy and economical to manufacture partand is such that it lends itself to being made extremely rugged anddurable.

The lower female section L of my collar R is an elongate, cylindrical,vertically extending part having a lower pin portion 40l with a centrallongitudinal ow passage 41, a central portion 42 and an upper portion43.

The lower pin portion 40 is externally threaded and is adapted to beengaged in an internally threaded box 44 in the upper end of a relatedtool or stand of drill pipe 45 occurring below the collar R.

The flow passage 41 is the same in diametric extent as the ow passage 20in the upper section U.

The central portion 42 corresponds in outside diameter with the boxportion 21 of the section U and is of considerable longitudinal extent.

The upper portion 43 is less in diametric extent than the centralportion 42 and is equal or slightly greater in diametric extent than themajor diameter of the threads 29 on the upper central portion 25 of thesection U. The portion 43 defines an annular, upwardly disposed stopshoulder 46. The upper end portion 43 defines a flat, axially upwardlydisposed upper end 47 on the section L.

The section L is provided with a first, enlarged, upper bore 50corresponding in diameter and in longitudinal extent with and slidablyreceives the lower central portion 26 of the upper section U, and alower, secondary bore 51 continuing downwardly from the upper primarybore 50 corresponding in diametric and longitudinal extent with andslidably receiving the portion 27 of the section U.

The upper portion 43 of the section L is slightly greater inlongitudinal extent than that portion of the lower central portion 26 ofthe section U in which the shear pin grooves 31 occur and normallyoverlies the shear pin grooves. The portion 43 is provided with a numberof axially spaced, annular rows of circumferentially spaced, axiallyextending shear pin-receiving openings 55, equal in number with thenumber of grooves 31 in the section U and in common radial planes withthe grooves 31 so that the inner ends of the openings 55 are in registerand communicate with the grooves 3.1.

The openings 55 of each row of openings are circumferentially offsetfrom the openings in the other row or rows of openings 55 so that theseveral openings 55 of the several rows of openings arecircumferentially offset from each other and none of said openings arein vertical alignment with respect to the longitudinal axis of theconstruction.

The upper portion of the central portion 42 of the section L is providedwith a plurality (three) of elongate, longitudinally extending, radiallyinwardly and outwardly opening slots 56 corresponding in circumferentialplacement and longitudinal extent with the ats 32 on the lower centralportion 26 of the section U and in which elongated flat engaging keys orblocks 57 are arranged and The blocks 57 are equal or slightly less inlateral extent than the flats 32 and have at, radially inwardly disposedbearing surfaces 58 which establish at, sliding bearing engagement onrelated ats 32 of the section U, when the construction is assembled andas clearly illustrated in the drawings.

The blocks 57 are fixed in the openings 56 by welding 58.

In addition to the foregoing, the construction we provide includessealing rings, such as O-rings, 59 engaged in the ring grooves 35 in thesection U to normally seal in the lower bore of the section L; shearpins 60 in all or a predetermined number less than all of the openings55 in the section L and entering the grooves 31 in the sectlon U, and ashear pin retaining sleeve carried by the section U and engaging thesection L and the pins 60 carried thereby.

The shear pins 60 are simple, cylindrical, elongate metal shear pinscorresponding in diametric extent with the diameter of the openings 55and the lateral extent of the grooves 31 and corresponding inlongitudinal extent with the combined longitudinal extent of theopenings 55 and depth of the grooves 31. The pins 60 are slidablyengaged in and through the openings, from the exterior of the section Land into engagement in the grooves 31.

The retaining sleeve 70 is an elongate sleeve corresponding inlongitudinal extent with the upper central portion 25 of the section Uand corresponds in inside diametric extent with the outside diameter ofthe upper portion 43 of the section L. The Sleeve is provided withinternal threads 71 in its lower portion to cooperatively engage thethreads 29 on the section U.

With the structure and the relationship of parts thus provided, it willbe apparent that the sleeve 70` can lbe shifted from a normal downposition where it overlies the upper portion 42 of the section L andholds the shear pins captive in the openings 55 and grooves 31, to an upposition, as shown in FIG. 3 of the drawings where the openings S andpins 60 are uncovered and accessible so as to facilitate easy andconvenient engagement of the pins 60 in the construction.

When the sleeve 70 is in its normal or down position, it is held andretained in that position adjacent the shoulder 46 by the threads 29-71.

It is to be noted that the seal established between the sections U and Lby the sealing rings 59 and which prevents leakage of drilling uid fromwithin the structure (in the passable fluid course between the sections)occurs downstream of the slots 56 in which the blocks 57 are arranged,downstream of the shear pin openings 5S and downstream of the sleeve 70.Accordingly, each and all of the parts and portions of the constructionwhich might be adversely affected by the presence of drilling fluid orthe iuid pressures within the construction, are downstream from thesealing means between the sections and are unaffected thereby.

lt is to be further noted that, rather than providing a single shearpin, I provide a multiplicity of shear pin receiving openings of acommon size and in which any desired number of shear pins can beengaged. With such -a combination and relationship of parts, the tensileholding force afforded by the collar can be varied as circumstancesrequire without modifying the construction or without having to maintaina supply of shear pins of different strength, which would be required ifa single shear pin construction was provided and the holding strength ofthe construction had to be changed.

Another very important feature found in the provision of a multiplicityof shear pins resides in the fact that the shearing forces are dividedup and distributed about the tool at a multiplicity of different pointsand are not sufficient at any one point to cause collapsing, tearing orscarring of the collar sections, as would be the case in a single shearpin construction.

Circumferential spacing of the shear pin opening in each annular row ofopenings from the openings in adjacent rows of openings further enhancesthe abovenoted features of dividing and distribution of forces.

In operation, the structure R is assembled and arranged in the string oftubing S in the manner illustrated in FIG. 2 of the drawings.

When and if excessive tension is applied to the string, the uppersection U shifts upwardly relative to the lower section L, shearing thepins 60 and allowing for free axial separation of the sections and theportion of the string S occurring above and below the collar.

Following such release of the collar, the upper section U, with itsdirectly related portion of the string S, is removed or pulled from thewell in a conventional manner and the lower section L and its directlyrelated portion of the string S and/or tool can be freed for easyremoval by backscuttling, hailing or otherwise removing the gravel, orthe like, which freezes or holds it in the well and then pulling it fromthe well. lf necessary, the portion of the string left in the well canbe' cut up and fished from the well.

In either event, the location of the break and the amount of tubing leftin the well is predetermined and so that the extent of the retrievingand/or fishing operation, which must be performed, is predetermined andmaintained to tolerable and economically feasible levels.

In FIGS. 8, 9 and 10 of the drawings, I illustrate a modified form ofthe invention, wherein a captive ring with circumferentially spacedshear pin receiving openings 101 is engaged in the groove 31 in theupper part of the lower central portion 26 of the upper section Uf'. Thering 100 is rotatably engaged in the groove 31 and the openings 101therein are spaced axially and circumferentially spaced to register withthe shear pin opening 55 in the upper portion 43 of the section L.

In practice, the ring 100 is made up of two semicircular half sections,as shown in FIG. 9. The half sections are arranged in the `groove 31 andare suitably welded together, as at 102.

With the above structure, it will be apparent that the ring 100 is heldcaptive in the groove 31 and is slidable therein for rotative movementrelative to the upper section U.

The openings 55 in the section L' and the openings 101 in the ring 100secure their related ends of the shear pins 60 snugly.

With the above construction, the radial inner end portions, as well asthe radial outer end portions of the shear pins 60 are held captive andin such a manner that they are not permitted or allowed to distort, coldflow and prematurely tear when subjected to major, but less thanyielding shearing forces.

In the rst form the invention, the inner end portions of the pins 60 arenot held captive about their circumferential opposite sides in thegrooves 31 and are free to cold flow, distort and tear in such a manneras to become weakened, if and when they are subjected to major, but lessthan designed yielding shearing forces.

The ring 100 in the modified form of the invention can be provided withany desired number of openings 101, which openings can be spaced axiallyand circumferentially of the rings in any predetermined pattern and tocooperate with the pattern of opening 55 in the section L.

The modified form of my invention illustrated and described above is themost desirable and preferred form and carrying out of the invention.

Having described only typical preferred forms and applications of myinvention, I do not wish to be limited or restricted to the specificdetails herein Set forth, but wish to reserve to myself anymodifications and/ or variations thereof that may appear to thoseskilled in the art.

Having described my invention, I claim:

1. A releasing collar engageable with and between upper and lower,adjacent, axially aligned stands of tubing in a fluid conducting tubingstring including, an elongate, cylindrical, vertically extending, uppersection with a central, longitudinal ow passage, upper connecting meansat its upper end to connect with the upper stand of tubing, threadsabout the exterior of the section and spaced above the lower endthereof, an annular, radially outwardly opening channel spaced below thethreads, a plurality of circumferentially spaced, elongate, axiallyextending, radially outwardly facing flats below the channel andannular, radially outwardly disposed sealing means about the exterior ofthe said upper section below said flats, an elongate cylindrical,vertically extending lower section with a central longitudinal owpassage, lower connecting means at its lower end to connect with thelower stand of tubing, a central bore slidably receiving the lowerportion of the upper section and cooperatively engaged by said sealingmeans, a plurality of circumferentially spaced blocks with fiat,radially inwardly disposed bearing faces carried by the lower sectionand normally establishing flat, sliding bearing engagement on the flats,circumferentially spaced, radially extending shear pin openings in saidlower section about the blocks and in a common radial plane with saidchannel, elongate radially extending shear pins engaged in the shear pinopenings and extending radially inwardly into the channel and aretaining sleeve engaged with the threads on the upper section to becarried thereby and engaged about the lower section to overlie saidopenings and stop radial outward shifting of said shear pins.

2. A structure as set forth in claim 1 wherein the lower end portion ofthe upper section which carries the sealing means is less in diameterthan the portion thereof in which said flats are established and theplanes of said tlats are substantially tangential with the outerperiphery of said lower end portion, said bore having upper and lowerportions, said lower portion corresponding in axial and diametric extentwith the lower portion of the lower end portion of the upper section andsaid upper po-rtion corresponding in diametric extent with the upperportion of the bore.

3. A structure as set forth in claim 1 wherein the lower end portion ofthe upper section which carries the sealing means is less in diameterthan the portion thereof in which said ats are established and theplanes of said flats are substantially tangential with the outerperiphery of said lower end portion, said bore having upper and lowerportions, said lower portion corresponding in axial and diametric extentwith the lower portion of the lower end portion of the upper section andsaid upper portion corresponding in diametric extent with the upperportion of the bore, said blocks being engaged in radial slots in thelower section to engage the ats and xed in said slots by welding.

4. A structure as set forth in claim 1 wherein, the upper section has anupper end portion in which said upper connecting means is arranged, anelongate upper intermediate portion of reduced diameter and having saidthreads about the lower end portion thereof, a lower intermediateportion of less diametric extent than the upper intermediate portion andin which said channel and flats are established and a lower end portionwhich carries said sealing means, said bore having a lower portioncorresponding in diametric and longitudinal extent with the lower endportion of the upper section, and an upper portion corresponding indiametric and longitudinal extent with the lower intermediate portion,the minor diameter of the threads being substantially equal to thediameter of the upper intermediate portion, the outside diameter of theupper end portion of the lower section being substantially equal to themajor diameter of the threads, said retaining sleeve having an upperthreaded portion to engage the threads and a lower skirt portionslidably engageable with and about the said upper portion of the lowersection, said sleeve being substantially equal in longitudinal extentwith the upper intermediate portion.

5. A structure as set forth in claim 1 wherein, the upper section has anupper end portion in which said upper connecting means is arranged, anelongate upper intermediate portion of reduced diameter and having saidthreads about the lower end portion thereof, a lower intermediateportion of less diametric extent than the upper intermediate portion andin which said channel and flats are established and a lower end portionwhich carries said sealing means, said bore having a lower portioncorresponding in diametric and longitudinal extent with the lower endportion of the upper section, and an upper portion corresponding indiametric and longitudinal extent with the lower intermediate portion,the minor diameter of the threads being substantially equal to thediameter of the upper intermediate portion, the outside diameter of theupper end portion of the lower section being substantially equal to themajor diameter of the threads, said retaining sleeve having an upperthreaded portion to engage the threads and a lower skirt portionslidably engageable with and about the said upper portion of the lowersection, said sleeve being substantially equal in longitudinal extentwith the upper intermediate portion, said ats occurring on planessubstantially tangential with the periphery of the lower end portion ofthe upper section whereby the lower end portion of the upper section canmove freely by the blocks upon axial shifting of the sections.

6. A structure as set forth in claim 1 which includes radially outwardlyopening channels in the upper section in axial spaced relationship withthe first-mentioned channel and said lower section includes annular rowsof circumferentially spaced radial openings in common planes with thechannels, the openings in each row of openings being circumferentiallyoffset from the openings in the other rows of openings, and shear pinsengaged in selected openings in the rows of openings, said shear pinsbeing of uniform shear and establishing uniform sliding bearingengagement in the holes and in the channels whereby the holding forceafforded by the several pins is cumulative.

7. A structure as set forth in claim l wherein, the upper section has anupper end portion in which said upper connecting means is arranged, anelongate upper intermediate portion of reduced diameter and having saidthreads about the lower end portion thereof, -a lower intermediateportion of less diametric extent than the upper intermediate portion andin which said channel and llats are established and a lower end portionwhich carries said sealing means, said bore having a lower portioncorresponding in diametric and longitudinal extent with the lower endportion of the upper section, and an upper portion corresponding indiametric and longitudinal extent with the lower intermediate portion,the minor diameter of the threads being substantially equal to thediameter of the upper intermediate portion, the ouside diameter of theupper end portion of the lower section being substantially equal to themajor diameter of the threads, said retaining sleeve having an upperthreaded portion to engage the threads and a lower skirt portionslidably engageable with and about the said upper portion of the lowersection, said sleeve being substantially equal in longitudinal extentwith the upper intermediate portion, said structure having radiallyoutwardly opening channels in the upper section in axial spacedrelationship with the firstmentioned channel and said lower sectionincluding annular rows of circumferentially spaced radial openings in acommon plane with the channels, the openings in each row of openingsbeing circumferentially offset from the openings in the other rows ofopenings, and shear pins engaged in selected openings in the rows ofopenings, said shear pins being of uniform shear and establishinguniform sliding bearing engagement in the holes and in the channelswhereby the holding force afforded by the several pins is cumulative.

8. A structure as set forth in claim 1 wherein, said sealing meansincludes a plurality of axially spaced, radially outwardly openinggrooves in the upper section and sealing rings engaged and sealing inthe grooves and engaging and sealing in the bore.

9. A structure as set forth in claim 1 wherein, the upper section has anupper end portion in which said upper connecting means is arranged, anelongate upper intermediate portion of reduced diameter and having saidthreads about the lower end portion thereof, a lower intermediateportion of less diametric extent than the upper intermediate portion andin which said channel and flats are established and a lower end portionwhich carries said sealing means, said bore having a lower portioncorresponding in diametric and longitudinal extent with the lower endportion of the upper section, and an upper portion corresponding indiametric and longitudinal extent with the lower intermediate portion,the minor diameter of the threads being substantially equal to thediameter of the upper intermediate portion, the outside diameter of theupper end portion of the lower section being substantially equal to themajor diameter of the threads, said retaining sleeve having an upperthreaded portion to engage the threads and a lower skirt portionslidably engageable with and about the said upper portion of the lowersection, said sleeve being substantially equal in longitudinal extentwith the upper intermediate portion, said structure having radiallyoutwardly opening channels in the upper section in axial spacedrelationship with the first-mentioned channel and said lower sectionincluding an annular row of circumferentially spaced radial openings ina common plane with each channel, the openings in each row of openingsbeing circumferentially offset from the openings in the other rows ofopenings, and shear pins engaged in selected openings in the rows ofopenings, said shear pins being of uniform shear and establishinguniform sliding bearing engagement in the holes and in the channelswhereby the holding force afforded by the several pins is cumulative,said sealing means including a plurality of axially spaced, radiallyoutwardly opening grooves in the upper section and sealing rings engagedand sealing in the grooves and engaging and sealing in the bore.

10. A structure as set forth in claim 1 wherein, the upper section hasan upper end portion in which said upper connecting means is arranged,an elongate upper intermediate portion of reduced diameter and havingsaid threads about the lower end portion thereof, a lower intermediateportion of less diametric extent than the upper intermediate portion andin which said channel and flats are establishing and a lower end portionwhich carries said sealing means, said bore having a lower portioncorresponding in diametric and longitudinal extent with the lower endportion of the upper section, and an upper portion corresponding indiametric and longitudinal extent with the lower intermediate portion,the minor diameter of the threads being substantially equal to thediameter of the upper intermediate portion, the outside diameter of theupper end portion of the lower section being substantially equal to themajor diameter of the threads, said retaining sleeve having an upperthreaded portion to engage the threads and a lower skirt portionslidably engageable with and about the said upper portion of the lowersection, said sleeve being substantially equal in longitudinal extentwith the upper intermediate portion, said flats occurring on planestangential or spaced radially outward of the periphery of the lower endportion of the upper section whereby the lower end portion of the uppersection can move freely by the blocks upon axial shifting of thesection, said blocks being engaged in radial slots in the lower sectionto engage the ats and fixed in said slots by welding, said structurehaving radially outwardly opening channels in the upper section in axialspaced relationship with the first-mentioned channel and said lowersection including annular rows of circumferentially spaced radialopenings in common planes with the channels, the openings in each row ofopenings being circumferentially offset from the openings in the otherrows of openings, and shear pins engaged in selected openings in therows of openings, said shear pins being of uniform shear andestablishing uniform sliding bearing engagement in the holes and in thechannels whereby the holding force afforded by the several pins iscumulative, said sealing means including a plurality of axially spaced,radially outwardly openings grooves in the upper section and sealingrings engaged and sealing in the grooves and engaging and sealing in thebore.

11. A structure as set forth in claim 1 which includes an annularcaptive ring engaged in said channel for relative rotation therein andhaving openings registered with the openings in the lower section andslidably receiving the pins.

12. A structure as set forth in claim 1 wherein the lower end portion ofthe upper section which carries the sealing means is less in diameterthan the portion thereof in which said ats are established and theplanes of said flats are substantially tangential with the outerperiphery of said lower end portion, said bore having upper and lowerportions, said lower portion corresponding in axial and diametric extentwith the lower portion of the lower end portion of the upper section andsaid upper portion corresponding in diametric extent with the upperportion of the bore, an annular captive ring engaged in said channel forrelative rotation therein and having openings registered with theopenings in the lower section and slidably receiving the pins.

13. A structure as set forth in claim 1 wherein the lower end portion ofthe upper section which carries the sealing means is less in diameterthan the portion thereof in which said flats are established and theplanes of said flats are substantially tangential with the outerperiphery of said lower end portion, said bore having upper and lowerportions, said lower portion corresponding in axial and diametric extentwith the lower portion of the lower end portion of the upper section andsaid upper portion corresponding in diametric extent with the upperportion of the bore, said blocks being engaged in radial slots in thelower section to engage the ats and xedV in said slots by welding, anannular captive ring engaged in said channel for relative rotationtherein and having openings registered with the openings in the lowersection and slidably receiving the pins.

14. A structure as set forth in claim 1 wherein the upper section has anupper end portion in which said upper connecting means is arranged, anelongate upper intermediate portion of reduced diameter and having saidthreads about the lower end portion thereof, a lower intermediateportion of less diametric extent than the upper intermediate portion andin which said channel and flats are established and a lower end portionwhich carries said sealing means, said bore having a lower portioncorresponding in diametric and longitudinal extent with the lower endportion of the upper section, and an upper portion corresponding indiametric and longitudinal extent with the lower intermediate portion,the minor diameter of the threads being substantially equal to thediameter of the upper intermediate portion, the outside diameter of theupper end portion of the lower section being substantially equal to themajor diameter of the threads, said retaining sleeve having an upperthreaded portion to engage the threads and a lower skirt portionslidably engageable with and about the said upper portion of the lowersection, said sleeve being substantially equal in longitudinal extentwith the upper intermediate portion, an annular captive ring engaged insaid channel for relative rotation therein and having openingsregistered with the openings in the lower section and slidably receivingthe pms.

15. A structure as set forth in claim 1 wherein, the upper section hasan upper end portion in Iwhich said upper connecting means is arranged,an elongate upper intermediate portion of reduced diameter and havingsaid threads about the lower end portion thereof, a lower intermediateportion of less diametric extent than the upper intermediate portion andin which said channel and flats are established and a lower end portionwhich carries said sealing means, said bore having a lower portioncorresponding in diametric and longitudinal extent with the lower endportion of the upper section, and an upper portion corresponding indiametric and longitudinal extent with the lower intermediate portion,the minor diameter of the threads being substantially equal to thediameter of the upper intermediate portion, the outside diameter of theupper end portion of the lower section being substantially equal to themajor diameter of the threads, said retaining sleeve having an upperthreaded portion to engage the threads and a lower skirt portionslidably engageable with and about the said upper portion of the lowersection, said sleeve being substantially equal in longitudinal extentwith 'the upper intermediate portion, said ats occurring on planessubstantially tangential with the periphery of the lower end portion ofthe upper section can move freely by the blocks upon axial shifting ofthe sections, an annular captive ring engaged in said channel forrelative rotation therein and having openings registered with theopenings in the lower section and slidably receiving the pins.

(References on following page) 13 14 References Cited FOREIGN PATENTS121,739 3/1958 U.S.S.R.

UNITED STATES PATENTS Reed 285-2 REINALDO P. MACHADO, Primary ExaminerDardelet 287--125 Claypool et a1 285 3 5 D. W. AROLA, Asslstant ExammerClark 285-2 U.S. C1. X.R.

Treese 285-2 285-330, 351, 286

